Ansys Meshing – Method

Written by cfd.ninja

April 11, 2020

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Source: Ansys

 

By default, the application uses the Automatic Method control, which attempts to use sweeping for solid models and quadrilateral element generation for surface body models. If solid bodies can’t be swept, the body is meshed with the Patch Conforming Tetrahedron mesher.

You can preview the bodies that can be swept meshed by right-clicking Mesh on the Tree Outline and choosing Show>Sweepable Bodies from the context menu.

Scoping a mesh method control (Sweep or MultiZone) is a way to force a body to be meshed with Sweep or MultiZone. To use the MultiZone mesh method in place of Sweep, turn on Tools>Options>Meshing>Meshing: Use MultiZone for Sweepable Bodies. When using MultiZone in place of Sweep, Sweepable bodies are meshed with MultiZone.

If you select the Tetrahedrons method, an all tetrahedral mesh is created.

If you select the Hex Dominant method, a free hex dominant mesh is created. If you are interested in a hex mesh, this option is recommended for bodies that cannot be swept. To preview any bodies that can be swept, click Mesh on the Tree Outline and right-click the mouse. Select Show> Sweepable Bodies from the context menu to display bodies that fulfill the requirements of a sweepable body (other than axis sweeping).

If you select the Sweep method, a swept mesh is forced on “sweepable” bodies (including axis-sweepable bodies, which are not displayed when you use the Show Sweepable Bodies feature). The mesher will fail if a swept mesh cannot be generated on a body with a Sweep Method control.

The MultiZone mesh method provides automatic decomposition of geometry into mapped (sweepable) regions and free regions. When the MultiZone mesh method is selected, all regions are meshed with a pure hexahedral mesh if possible. To handle cases in which a pure hex mesh will not be possible, you can adjust your settings so that a swept mesh will be generated in structured regions and a free mesh will be generated in unstructured regions.

The Cartesian method creates unstructured hexa mesh of mostly uniform size, aligned to the specified coordinate system, and fits it to the geometry. The element size should be smaller than the thickness of the model to prevent the mesher from defeaturing (not capturing) that portion of the model. Alternatively, the defeaturing could be helpful to eliminate “dirty” geometry smaller than the element size.

The Layered Tetrahedrons mesh method creates unstructured tetrahedral mesh in layers based on a specified layer height and fits it to the geometry.

This method can be used for simulating the printing process in additive manufacturing as the build parts must conform to a mesh with fixed step sizes in the global Z direction.

The meshing process involves the following approach:

  • An initial surface mesh is generated based on the settings defined.
  • The mesher generates mesh layers based on the layer height specified. The starting layer is the z-location of the plane from which the mesh layers will be generated.
  • Nodes on the geometry within the tolerance specified (Relative Tolerance) to the layer plane are projected to the plane during the initial layering operation.
  • Feature nodes and corner nodes determined based on the Feature Angle and the Corner Angle, respectively, will be preserved.
  • Problematic sliver faces are identified based on Sliver Triangle Height and are collapsed or fixed to improve quality.
  • Geometry faces overlapping the layer plane are identified based on the Overlapping Angle and are inflated. Additionally, geometry faces close to the layer planes which will lead to bad quality tets are identified based on the Layer Height and proximity to the plane. These faces will be inflated away from the layer planes to create space for better quality tets based on the Inflate Relative Tolerance value specified.
  • The improved surface mesh is then filled with tetrahedral mesh conforming to the mesh layers and the tetrahedral mesh quality is improved.

 

In this tutorial, you will learn how to use the Method option from Ansys Meshing using Ansys Meshing.

 

Do you want to learn to generate a Fine Mesh?

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